Oracle is now the leading JSON database, not only with a binary JSON datatype (allowing true piece-wise updates on disk and fast 'jump-navigation for super fast queries), but also JSON Schema support (for schema enforcement, type casting, to describe database objects and auto-generate relational views over JSON) and with JSON Duality it's possible to access (read/write) the same data as table as well as as (MongoDB compatible) collections.
I am trying hard to see who could be the target audience for such a thing.
My best guess is engineers who are not currently employed, but who would like to up specifically their Oracle skills, as opposed to other valuable alternatives like Postgres.
Postgres doesn't even hold a candle to the OLTP performance that Oracle is capable of. It is probably decades ahead of Postgres in terms of technology. Oracle had multi-instance capability 22 years ago. Robust multi-instance support still seems to elude Postgres. Postgres high availability and failover capabilities are laughable.
Sure, Postgres is much easier to setup and tune (because it does much less compared to Oracle anyway), but it's not going to dethrone Oracle anytime soon when it comes to powering the most demanding OLTP workloads (like stock exchanges and telecom) out there.
Simple VMs for testing purposes are useful for infrastructure consultants and developers, in niches where the products support Oracle as deployment database.
It's a smaller and smaller audience, because of cloud taking over, but someone still needs it.
smaller and smaller, really? my friends (students as me) like it a lot for its simplicity and maturity: look at those new features inside, there is much more than the MERGE command ;D and this is the database we'll have to work with in large companies.
This is not "the next version available for free", this is them refreshing the free offering they've had for more than a decade (previously known as Oracle XE). They do that every few years.
XE was released to match SQLServer Express, which in turn was released because MySQL and PostgreSQL were eating their lunch among small dev shops (they still are). Nowadays nobody cares, unless they have to maintain some legacy product.